Anchoring fibrils, a distinct class of fibrils of extracellular connective tissue, were found in normal canine respiratory tree in association with: basal cells and special type cells of trachea and bronchi; ciliated cells and basal cells of bronchioles; and ductal cells, secretory cells and myoepithelial cells of tracheobronchial glands. Anchoring fibrils reinforce the attachment of the epithelial basal lamina to the underlying connective tissues.